1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing a polarizable electrode for electric double layer capacitor, which is used when manufacturing the polarizable electrode for electric double layer capacitor.
2. Description of the Related Art
For example, JP-B2-3776875 (see paragraphs 0012, 0016) discloses a technology regarding a method for manufacturing a polarizable electrode for electric double layer capacitor. According to the technology, raw materials including a carbonaceous powder, a conductive assistant, and a binder are mixed and kneaded into kneaded materials, and the kneaded materials are finely divided to obtain molding materials. The molding materials are formed into a sheet form by a calendar molding machine, and the molded sheet is rolled to manufacture an electrode sheet for electric double layer capacitor.
In this case, during a pretreatment process before the molding materials are formed into a sheet form by the calendar molding machine, the finely-divided, granulated molding materials are contained in a container of a mixing machine (mixer) and mixed with binding assistants (for example, IPA (isopropyl alcohol) added thereto. The container has a cylindrical shape and is hermetically sealed. When the container is rotated in the circumferential direction while being swung upward and downward, the materials contained therein are mixed with each other. In this manner, by mixing the granulated molding materials and the binding assistants with each other by using the hermetically sealed container, the binding assistants are not vaporized outside the container, preventing any change in the content ratio. Therefore, the materials contained in the container are mixed as uniform as possible. With this, the quality of the molding materials is stabilized, and it is thus possible to efficiently manufacture a polarizable electrode sheet.
According to the technology disclosed in JP-B2-3776875, when mixing the granulated molding materials and the binding assistants with each other by using the hermetically sealed container, the container is rotated in the circumferential direction while being swung upward and downward. However, the granulated molding materials may sometimes adhere with each other into a lump form. When such molding materials, in which the granulated molding materials are lumped by adhering themselves to each other, are formed into a sheet form by the calendar molding machine, problems such as porosities (voids), cracks, breakage, or swelling of a sheet are caused.
The present invention has been made in view of the problems described above. An object of the present invention is to provide a method and apparatus for manufacturing a polarizable electrode for electric double layer capacitor capable of preventing porosities, cracks, or breakage of a sheet as much as possible when molding materials are formed into a sheet form and improving the yield of the molding materials.